Machine tool and operating circuit therefor



Oct. 20, 1953 R. l. EYLER MACHINE 'rooz. AND OPERATING CIRCUIT THEREFOR 5 Sheets-Sheet 1 Filed June 30, 1949 gvwwvbob I EYLER 3% JM q z/j gm Oct. 20, 1953 R. EYLER 4g 7 2,655,670

MACHINE TOOL. AND OPERATING CIRCUIT THEREFOR Filed June 30, 1949 5 Sheets-Sheet 2 i w, JMJZW q. LI

Oct. 20, 1953 R. I. EYLER 2,655,670

MACHINE TOOL AND OPERATING CIRCUIT THEREFOR Filed June 30, 1949 5 Sheets-Sheet 3 ROY I. EYLE R Oct. 20, 1953 R. 1. EYLER 2,655,670

MACHINE TOOL AND OPERATING CIRCUIT THEREFOR Filed June :50, 1949 s Sheets-Sheet 4' ROY l. EYLER w, X/M Jaw Oct. 20, 1953 R. l. EYLER 2,655,670

MACHINE TOOL AND OPERATING CIRCUIT THEREFOR Filed June 30, 1949 5 Sheets-Sheet 5 LSZOiLSMi 2a4 I ROY l. EYLER Patented Oct. 20, 1953 MACHINE TOOL AND OPERATING CIRCUIT THEREFOR Roy I. Eyler, Waynesboro, Pa., assignor to Landis Machine Company, Waynesboro, Pa., a corporation of Pennsylvania Application June so, 1949, Serial No. 102,363

6 Claims.

Thi invention concerns metal working machines and in particular machines for performing machining operations on widely separated portions of an elongated work piece, and control systems therefor.

The present invention is an improvement on certain features of the machine shown and described in the pending application of Harry L. Eerkey and George E. Hieber, S. N. 747,756, filed May 13, 1947, for Automatic Pipe Machine. The control system of the machine described in the aforesaid application has been improved by replacing the mechanically-held electrical relays with relays of the ordinary type. This reduces the number of relays required by a considerable number, and, permits a general simplification of the entire control circuit. Another advantage is that the failure to function of the mechanicallyheld relays may sometimes occur due to mechanical wear and such failure can cause the operating cycle to be confused. As a result, certain of the operations are performed out of their proper sequence, which may damag the machine. The use of the ordinary relay insures that the relay will, for instance, be held closed during the entire period or" time required for it to be held closed. This is done electrically and by the same current which causes the hydraulic valves to function properly for the correct sequence of operations. For such a relay to fail to hold, it would be necessary for the current to fail, in which case the machine would stop. With the mechanically-held relays, on the other hand, it is possible for the relay to fail mechanically while the electric current continues to drive the machine, but in incorrect and erratic sequence.

To insure the proper and most eificient operation of the relays, an entirely new control system has been devised for th machine. This new and simplified control system has several other additional distinct and important advantages over that previously used, among which are the possibility of opening and closing either of the two chucks independently of the machine cycle for setting-up purposes, the possibility of causing either of the two carriages to move through their operating cycle while th rest of the machine is at rest and the possibility of causing either of the two machining units to move completely through one operating cycle and stop.

Accordingly it is an object of the present invention to provide an improved control circuit for a machine tool comprising a work handling unit and one or more work forming units, all of which are operated in timed relation with each other.

Another object of the invention is to provide such a control circuit which will effectively employ electrically-held relays in all cases to assure proper sequential operation of the various mechanisms at all times.

A further object of the invention is to provide a control system for a complex machine tool comprising one or more operating units and a work handling unit, which system is selectively useful for the automatic operation of the entire machine, for the operation of an individual unit of the machine or for the operation of a particular mechanism or portion of a unit.

Other objects and advantages will be apparent from the following description of the invention and from the accompanying drawings in which:

Figure 1 is a top plan view of the complete machine.

Figures 2A, 2B, 2C and 2D constitute a diagram of the hydraulic and electrical control circuit of the machine.

In Figure 1 the central unit I00 is the transfer table of the machine which serves to convey the work pieces successively to several index stations along the rails I02. Rails I02 are supported at both ends by a series of pedestals I04 and I06. A chain sprocket I08 is mounted in each rail at the end supported by pedestals I04. Sprockets I08 are arranged for rotation with and keyed to a shaft I I0 which is made up of several short shafts coupled together to connect all of the sprockets I08 for unitary rotation. Sprockets I I2 are mounted in rails I02 at the ends supported by pedestals I06 and are arranged for rotation with and keyed to a shaft H4 which is composed of several short shafts coupled together to connect all of the sprockets I I2 for unitary rotation.

Each pair of sprockets I08 and I I2 is connected by a chain I I6 (Figure 2B) so that they all rotate in unison. Such rotation is intermittent and may be accomplished by means of one or more hydraulic cylinders I I8 (Figure 2B) mounted in the interior of a rail or rails I02. The piston of cylinder II 8 is secured to a member I20 having tooth-like projections I22 on one side which projections are adapted to engage simultaneously with several rollers of chain I I5. Thus the actuation of cylinder I I8 in the outward direction propels chain I I6 and simultaneously rotates sprockets I08 and H2 and their shafts H0 and III. When the piston of cylinder H8 is withdrawn rearwardly the toothed member I20 slides ineffectually on chain I I6 and at the end of the stroke of the piston, engages another group of rollers in said chain preparatory for another propulsion of the chains H6. The number of members I20 driven by cylinders I I8 will depend upon the number of rails I02. Where there are five of such rails, as in Figure 1, two members I20 will be sufllcient. Chains I I6 are fitted in known manner with suitable lugs which are employed to engage the pipe or other elongated work piece which rests across the top surfaces of the rails I02 and parallel with shafts III] and H4. Thus the propulsion of chains IIG moves the pipe laterally for a predetermined distance equal to the stroke of cylinder II8, leaving the pipe at rest between outward strokes of said cylinder. The upper surfacm of the rails I02 are provided with depressions I26 into which the work piece falls after having been advanced by a stroke of cylinder H8. The distance between adjacent notches being equal to the length of a stroke of member I20.

A series of rollers I24 are mounted upon the pedestals I04. The depressions I26 in rails I02 permit the pipe being operated upon to be supported by rollers I24 when thep'ipe comes to rest at particular index station. Rollers I24 are driven by motors I28 to carry the pipe axially to the left as seen in Figure l. A similar 'set of rollers I30 are mounted adjacent the pedestals 105 to convey the pipe axially in the opposite direction, said rollers being driven for this purpose by the motors I32 mounted upon pedestals I00.

The above described transfer table is adapted to serve two work formin units, one of which, designated by the reference character 1'34 is located at the left side of the transfer table I as shown "in Figure 1, while the other, indicated generally at I30 is located at the right side of said table.

Since the two work-forming units I34 and I36 are'identic'al in construction andmode of operation a brief description of unit I34 should suffice for both. A complete, detailed description of these units may be found in the aboveinenti'oned copending application. For exemplarypurposes only, the units I34 and I36 are shown to be thread cutting machines. It should be understood that they may alternatively be ma'chines for performing such preliminary operations asfreaming, facing or taper-turning.

Unit I30 comprises a carriage! suitably supported by a bed I40 for slidin movement in a longitudinal direction, that is, perpendicularly towardand from the adjacent transfer table I00. A die head'I42 and a taper producing mechanism l'laresupported at the'front and rear ends respectively of the carriage I38. Forwardly of die head H2, bedflfl encloses a chuck I46 for gripping the cnd of the 'pipe'while it is being operated upon by the'die head I42. As described in the above mentioned application, chuck I46 employs grips which rec'ede below the level of rails I02 so thata pipe may be introduoedlaterally into gripping position.

Operation Briefly, the operation of the machine is'as follows. The pipe ortube to be operated upon is introduced by any convenient means onto the transfer table I09 at-the top of Figure 1 and is intermittently propel-led as above describeduntll it is supported by the rollers 124. These rollers "H4 convey the pipe axially until it abuts against a work stop I43 a-nlxed to thebed I40 of ma- III. At the next stroke of the index'mechanismthe pipe is carried to the following index station'at which it 'is 'in substantial alignment wth the axis of die head I42. At this point the pipe is automatically seized by the chuck I46 and held securely for the threading operation which is accomplished by the automatic advance of carriage I38 and the attached die head I42.

When the thread is finished, die head I42 opens automatically and is withdrawn rcaiwardly to clear the end of the pipe and permit the next indexing operation. The chuck I46 opens and the 'pipe is then moved intermittently in a downward direction as seen in Figure 1 until it rests upon the rollers I30. These rollers convey the pipe axially against a work stop I50 which is secured to the bed 152 of the right hand threading unit I33. With the extremity of the pipe thus located for the machining operation it is carried by the following index movement into substantial alignment with the carriage I54 and (lie head i56 of'the right hand unit. .At this position the pipe is seized by the chuck I58 and the abovedes'oribed threading operation is repeated, this time on the right hand end of the pipe. Thereafter, by a further movement of the index mechanismth'e finished work piece is discharged from the machine at the bottom of Figure l.

The control circuit shown in Figures 2A to 2D is arranged to perform the operation of threading upon the pipe and therefore includes the operation'of a threading head. If units for other types of machining are to be used, the circuit shown is equally applicable with the elimination of those parts necessary for the opening and closing of the die head and leadscrew nuts. As in the above-mentioned copending application, the parts of the circuit which energizes the spindle motors, roll motors and coolant and lubricating pump motors is omitted here since that is all "in accordance'with standard practice and has no effect upon the control circuit shown.

In'thisdiagra-m, to facilitate reading, the control relay coils have been designated as R6, R1 etc. These relays are all of the ordinary type and the contacts thereof are shown in their normal positions which they assume when the coil of the relay is not energized,

The contacts associated with each relay are given the same number as the relay but preceded by the letter-C instead of R. as 08A, 06B etc. It will be noted that most relay coils have more than one setof contacts. For instance relay coil R-Qactuates three contacts which will be found in'the circuits of solenoid 626A, relay coil R9 and relay coil R10. Limit switches are designated asetc. Manually operated switches are designated PBI, etc., -for push button switches and SWI.-'etc., for knife switches. The solenoids included in the circuit are given a number preceded by the letters and followed by either A or B as Sila -etc. The suffixes here designate opposite sides of the same valve so that if solenoid 8223A is energized, the valve associated therewith will be set'ln one position and if solenoid 52313 is energized, said valve will be set in the other position.

in order -to facilitate the reading of the'circults shown in Figs. 2A-2D the various electric lines have reference numbers 400-436 applied to where the particular lines run from one sheet --of drawing to another. For example line 40! connects a contact LSBA-on to a contact LSI3A on Fig. 2D.

The current for operating the controls is carried-by thetwowiresdesignated LI and L2. The control relays are connected in parallel across lines LI and I12. After the various electric motors have been started, the cycle start button and I58.

upper ends of cylinders I92 and I94 hold racks PB3 (Fig. 2C) or P134 is pressed to close a circuit LI--PBI6-PBI5PB3 or PB4-R1-L2, energizing relay R1. Energization of relay R1 opens contacts 010 and C1E and closes contacts 01A, 01B and C1D. Contacts C1C, C1D and C1E have no immediate effect on the cycle. Contacts C1B close a circuit LIPBI6PBI5-C1B- R1L2 to provide a holding circuit for the energization of relay R1 when pressure on the switch PB3 or PB4 is released. The presence of the two switches P133 and P34 is due merely to the desirability of having one of these cycle start switches at each of the machining units so that the cycle may conveniently be started from either end of the machine. The normally closed switches PBI5 and PBIG are for the purpose of stopping the operation of the machine without stopping the motors which drive the various parts of the machine. As will be seen later, the cycle Will continue to its end before stopping after either switch PBI5 or PBI6 is pressed. As is well understood in the art, a master stop button may be installed in the motor circuits to stop the entire machine instantaneously in case of emergency.

Closing of contacts C1A closes a circuit Ll-- LS IA(Fig. 2B) LS2-LS3-C1AR6-L2, energizing relay R6 and closing the five sets of contacts associated therewith. Closing of contacts C6B closes a circuit LlLS4B-C6B- LS2LS3--C1AR6--L2 to provide another circuit for energizing relay R6. The limit switches LS2 and LS3 are closed when the chucks are open and limit switch LS4 is closed on its contacts LS4B when the index mechanism is not fully extended, both of which conditions are present at this period in the cycle. Closing of contacts 06A closes a circuit LI-C6AS29B L2, energizing valve solenoid S2913.

As seen in Figure 1, the left hand machining unit I34 is driven by a motor I68 which is also employed to drive the attached two-pressure hydraulic pump I62. The right hand machining unit I36 is driven by a motor I84 which also drives the attached two-pressure pump I66. Pump I62 lifts hydraulic fluid from a reservoir I63 (Fig. 2B) and discharges it at low pressure into line I68 and at high pressure into line I10. Pump I66 lifts fluid from a reservoir I61 (Fig. 2C) and discharges it at low pressure into line I12 and at high pressure into line I14. Lines I and I14 lead to the sequence valves I16 and I18 respectively. These valves have no effect on the pressure or flow in the through lines I10 and E14 and their function is to permit fluid to pass into lines I80 and I82 respectively when the line pressure exceeds a predetermined value.

Lines I10 and I14 continue to regulate valves I84 and E86 respectively. As will presently be seen, lines I10 and I14 provide fluid for actuating the gripper mechanism so regulating valves I64 and I36 are provided to limit the pressure in lines I10 and I14 to a safe gripping pressure and to prevent crushing the pipe between the grips. Lines I10 and I14 lead, finally, to the distributing valves V28 and V respectively.

At the start of the operating cycle, the pistons of valves V28 and V25 are set to deliver fluid into lines I88 and I90 respectively. Lines I88 and I90 lead directly to the upper ends of cylin-,

ders I92 and I94 respectively, the pistons of which are attached to operating racks I96 and E98 respectively of the gripper mechanisms I46 Fluid existing under pressurein the I96 and I98 at the downward end of their strokes and thus the grips are held in open position.

Lines I68 and I12 connect respectively to the relief valves 200 and 202. Delivery lines 204 and 206 extend from valves 200 and 202 to check valves 208 and 2I0. Line 2I2 connects both valves 208 and 2I0 to the distributing valve V29. At the start of the operating cycle, valve V29 is set to deliver fluid through line 2I6 into the forward end I I9 of cylinder II8, the piston of which is employed to operate the index mechanism, as described above. Fluid existing under pressure in the forward end of cylinder I I8 holds the member I20 in retracted position. However, immediately after the start of the cycle of operation, as described above, the solenoid S293 is energized to shift the piston of valve V29. When this occurs, fluid is delivered through line 2I4 to the rearward end of cylinder II8 to start the index member I20 moving forward to its extended position, in the course of which movement the indexing chains II6 are propelled to carry the tubes being operated upon one station forwardly.

It should be noted that fluid from both pumps is used to actuate the index mechanism since a large volume of fluid is needed, especially if a number of indexing mechanisms are used. Slower operation can be obtained, however, by the use of either of the pumps if the other is, for any reason, not operating. The check valves 208 and 2I8 effectively close lines Y204 and 206 for such operation. Thus it is seen that either threading unit may be operated together with the transfer table and without the other unit.

Line 204 connects with line I88 through a check valve 2I8 and line 206 is connected to line I82 by a check valve 220. Branches of lines I86 and I82 lead to the solenoid-operated springreturn valves V39 and V40 respectively. The energization of solenoids S39 and S40 will close valves V39 and V40 to prevent fluid from entering lines 222 and 224 respectively to shift the positions of the pistons of relief valves 200 and 202.

Line I deliversfluid under pressure to the distributing valves V26 (Fig. 2A), V21 and V30. The piston of valve V21 is initialy set so that fluid is delivered through a line 226 to the lower end of a cylinder 228 to maintain leadscrew nut 229 of threading unit I34 in open position. Valve V26 is designed to occupy a neutral position when neither of its solenoids are energized, which is the present case, so that all lines leading to it are closed. Thus fluid is trapped without pressure in lines 230 and 232 leading respectively to the forward and rear ends of carriage operating cylinder 234 and the carriage I38 remains stationary.

The line I82 delivers fluid under pressure to the distributing valves V23 (Fig. 2D), V24 and V3I. The piston of valve V24 is set so that fluid is delivered through line 236 to the lower end of cylinder 238 to maintain the leadscrew nut 248 of threading unit I36 in open position. Valve V23, like valve V2 6, is closed when neither of its solenoids are energized and fluid is trapped with out pressure in lines 242 and 2544 leading respectively to the forward and rearward ends of carriage operating cylinder 246 and the carriage I54 remains stationary.

The beginning of the advance of the index mechanism described above operates limit switch LSI, opening its contacts LSIA and closing contacts LSIB. Opening of contacts LSIA opens the circuit Li-Ls|A Ls2-Le:- cuns-Lz ut relay R remains energized by means of the above-mentioned second circuit through contacts C63. The closing of contacts CCC closes a circuit LI-C8CRI6-L2 to energize relay Eli and close the four sets of contacts associated therewith. Contacts CISD have no immediate effect on the circuit. Contacts CIBC close a circuit LILSIBCI6C-R{6-L2 to provide a second circuit for energization of relay RI 6. The closing of contacts C ISA and CIBB closes the circuits LI-CI6A S39L2 and LI--C,I6B S 49 L2 respectively, energizing solenoids S39 and 844. As explained above, these valves will then be set to close lines 222 and 224 and thus prevent dumping the hydraulic pumps through relief valves 209 and 2.02. This insures that the full volume of the pumps i available to operate the various cylinders, beginning with the index y nder II8.

When contacts C6D close, they close a circuit LI-C6D-S3OA-L2. energizing solenoid 330A which shifts the piston of valve V38 so that fluid passes from supply line I80 through valve V30 and line 248 into the forward end of .a die head operating cylinder 250 throu h the stationary p ston rod thereof. The movable cylinder 250 thus is forced forwardly to close the die head I42 to its threading diameter. The details of one means of accomplishing this is shown and described in the co-pending application of Harry L. Berkey, Serial No. 597, 24, filed June 4, 1945, for Machine Tool. At the same time. fluid is being forced from the rear end of cylinder 250 through line 252 and valve V32 into exhaust line 254 whence it is returned to the reservoir.

Closing of contacts CIE closes a circuit LI-- CBE-SSIA-LL energizing solenoid SSIA and setting valve VII to pass .fluid from supply line I82 into line 258 and the forward end of the right hand die head operating cylinder 258 where the pressure it utilized as described above to close the die head I56 of the right hand threading unit I36 to thread-cutting position. Fluid is simultaneously forced from the rear end of cylinder 258 through line 250 and valve V3I into the exhaust line 262 by which it is carried back to the reservoir. The closing of both thread-cutting heads closes limit switches LSIB and LSI I.

The index mechanism, at the completion of its forward movement, actuates limit switchLS4B to open its contacts LS4B and close contact :LSIA. Opening of contacts 'LS4B opens the circuit LI-- LS4BC6B-Ls2-LS3-ClAR6-L2, de-energizing relay R6 and opening all of its five contacts. Contacts 0513, being in the last-named circuit have no eflect on the cycle. Opening of contacts CBA opens the circuit LI--C6AS2BB- L2, de-energizing solenoid 829B. Valve V22, however, does not alter its previous position so that pressure is maintained in therearward end of index cylinder IIB. Opening of contacts 06C opens the circuit LI--C6C,RI6-L2 but relay RIB remains energized by the above-mentioned second circuit through contacts CIIiC. Opening of contacts C6D opens the circuit LI-C6D- SJOA-L2, lie-energizing solenoid 820A, which has no effect .on valve V30. Opening of contacts CGE opens thecircuit LI-CBE-SB IA-L2 to deenerglze solenoid S2 IA also with noeffect on the associated valve.

The closing of contacts LS4A closes a circuit Li TS4A-IS5B -LS5B R8 L2. Limit switchm 1.85 and LS6 are closed on contacts .LSB andLSfiB respectively when the chucks I46 and I 58 for gripping the pipe are Open, which they are at this period in the cycle. The lastnamed circuit energizes relay R8, opening the normally closed contacts CBD and closing the remaining four normally open contacts associated with said relay. The opening of contacts CS1) has no effect on the cycle at this time. since this is the first .cycle of operation of the machine. In subsequent automatically repeating cycles, however, the opening of contacts C8D de-energises B. This is necesary in order to open the circuits LI-Cl4A-S28B-L2 and LICI4B-- S25B-L2 to de-energize S283 and 5253 during the automatically repeating cycle. The closing of contacts CBC closes a circuit LIPBIB PBII-C25B--CI2B-C8CR8L2 to provide a second circuit for the energization of relay R8. The closing of contacts C8A closes a circuit LI CI9AC8AS2 8A-L2, energizing solenoid 328A. The closing of contacts CBB closes a circuit LI- CIBA C813 525A L2, energizing solenoid 825A. Solenoids 328A and 525A operate to reverse the positions of valves V28 and V25. Fluid i thereforepumped through line 110, sequence valve I16, and regulating valve I84 to the valve V28 which is now Set to deliver the fluid thro line 264 to the lower end of gripper cylinder I92 to Iorce rack I06 upwardly and close the grips. Fluid is expelled from the upper end of cylinder 192 through line I88 and valve V28 to exhaus line 254. Pump I66 forces fluid through line I14. sequence valve I18 and regulating valve I85 to the valve V25, which is now set to deliver the fluid through line 266 to the lowerend of gripper cylinder I94 to force rack I88 upward and close the grips. Fluid is expelled from the upper end of cylinder I94 through line I and valve V25 to the exhaust line 254.

Since the large volume demand for the fluid to close the grips causes the pressure in lines I10 and I14 to drop below that in the secondary pressure lines 204 and 206, fluid passes from lines 204 and 208 through check valves 212 and 21,4 respectively into lines I10 and I14 to maintain at least the secondary pressure. When the cylindcrs are filled the pressure again rises, check valves 212 and 214 close, and the pressure in the gripping cylinders is that set by regulating valves I84 and I86.

Closing of contacts CBE closes a circuit LI 1S4AC21B-C8EC9.CRl 0-,L2, energizing relay RIO and closing the two sets of contacts associated therewith. The closing of contacts CIDA has no immediate eiie t on th c rcuit. while the closing of contacts CIIIB closes a circuit LILSI3A.LS8A-CIOB-RI 0L2 to provide a second circuit for the energizaticn of relay R10. This circuit includes contacts ,LSI-SA and LSSA of limit switches ISIS and LS8 respectively, which contacts are closed when the carriages .of both threading machines are in their rearmost positions. Closing of contacts 0813 also closes a circuit LILS4AC2'IBC8E-C2IC R22--L2 to energize relay R22 and close the two sets of contacts associated therewith, neither of which have any effect on the circuit at the present time. A second circuit to energize relay R22 is, however, closed by the closing of contacts 022B, namely: LI.LS4A-C2'IB-C8E--C9C CJOBC,22BR2 2L2.

The above-described closing of the grips of .both threading units operates the limit switches LS2, 1153,1185 and LS6, opening switches LS2 and LS3 and contacts LSSB and 'LSBB and closing contacts LSBA and 156A. The opening of contacts LSB and LS6B opens the circuit LI LS4ALS5BLS6BR8L2 but relay R8 remains energized by the above-described second circuit through contacts CBC. The opening of limit switches LS2 and LS3 has no immediate effect.

Closing of contacts LSEA closes a circuit LI- LS I 3ALS8A--LS9BLS5A-C I 0AR3L2 to energize relay R9, opening contacts C90 and closing contacts CSA and 08B. Opening of contacts 09C opens the circuit LILS4A-C2'IB C8E-C9CCIOB--C22B-R22L2. However, relay R22 remains energized by the circuit through CZIC. The opening of contacts CBC also opens the circuit LILS4AC2"lB-C8E- C9CRI8-L2 leaving relay 9I8 energized only by the circuit LILSI3A-LS8ACIBBRIO L2. The closing of contacts C9B closes a circuit L I --C9B-LS9BLS5AC I 0A-R9-L2 to provide a second circuit for energizing relay R8. Contacts 093 also close a circuit LIC8B CI6BRI8-L2 and a circuit LI--C9B-C22B- R22-L2 to provide holding circuits for relays RI?) and R22 respectively. The same contacts.

CSB also close a circuit LEC9BLSI4B LS6AC'22A-R2 l-LZ, energizing relay RZI, opening contacts C2IC and closing contacts CZlA and C253 closes of contacts CQA closes a circuit LIC9AS26A-L2, energizing solenoid 826A. Solenoid 826A shifts the piston of valve V26 to permit fluid under pressure to flow from supply line I 80 through valve V26 and Line 232 to the rear end of the left hand carriage operating cylinder 234. Due to this pressure in the rear endof cylinder 234, the left hand carriage I38 begins to advance toward the work to be threaded while the front end of cylinder 234 exhausts through line 230, valve V26 and line 254 to the reservoir.

Opening of contacts C2 IC opens the circuit I- LS lA-CZEBC8EC2IC R22-L2 but relay R22 remains energized by the above-named holding circuit through 0223. The closing of contacts (321B closes a circuit LiC2IB-LSI4B- LS6A-C22AR2IL2 to provide a second circuit for the energization of relay R2 I. Closing of contacts C2 IA closes a circuit LI C2 IA--S23A L2, energizing solenoid 823A. Solenoid 823A shifts the piston of valve V23 to permit fiuid to pass from supply line I82 through valve V23 and line 244 to the rear end of right hand carriage operating cylinder 246 by reason of which carriage I54 begins to advance toward the pipe to be threaded. At the same time, cylinder 246 exhausts through line 242, valve V23 and exhaust line 262 into the reservoir.

The advance of carriage I38 causes a dog 268, which is in contact with limit switch LS8 when the carriage I38 is in its rearmost position, to release said limit switch, opening contacts LSBA and closing contacts LSBB. The advance of carriage 154 causes a dog 216 which is in contact with the limit switch LSI 3 when the carriage I54 is at its rearmost position, to release said limit switch, opening contacts LSI3A and closing contacts LSI3B. The opening of these contacts LSBA and LSI3A opens the circuit LILSI3A- LS8ACI8BRiIl--L2, leaving relay RIO energized by the circuit LIC9B-CIOBR!8-L2. Opening of contacts LSBA and LSI3A also opens the circuit LI -LS I 3A--LS8ALS9B-LS5A C I 0AR3L2, leaving relay R9 energized by the circuit LI-C9BLS9BLS5AC I 8AR9-L2.

The continued advance of the two carriages causes the dogs 269 and 21I to actuate the limit switches LS9 and LS I 4 respectively, opening contacts LS9B and LSI 4B and closing contacts LSSA and LSI4A. The opening of contacts LSI4B opens the circuit LIC9BLSI4BLS6A C22A-R2 I-L2 and LIC2 I B-LS I 4B--LS6A C22A-R2I-L2, thus ole-energizing relay R2I and opening contacts CZIA and CZIB and closing contacts C2IC. The opening of contacts C2IA opens the circuit LIC2IA-S23A-L2 to de-energize solenoid 823A.

Since contacts C2IB are in the already open circuit LIC2 IB-LS I 4BLS6A--C22AR2 I L2, their opening at this time has no effect on the cycle. Closing of contacts C2IC closes the circuit LI --LS4A-C2IB-C8E+C2 ICR22L2 to provide another circuit for energizing relay R22. The opening of contacts LSBB opens the circuit LI C9B-LS9B--LS5AC I 8A-R8L2, de-energizing relay R9, opening contacts CSA and 09B and closing contacts CBC. The opening of contacts C8A opens the circuit LICQA-SZBA- L2, de-energizing solenoid S2 6A.

The de-energization of solenoids 823A and S26A causes the pistons of valves V23 and V26 to be freed to the action of the centering devices contained in these valves, which results in the closing of the valves and the cutting oif of the lines 230, 232, 242 and 244 to the respective carriage operating cylinders 234 and 246.

Carriage I38 therefore stops but its momentum results in the development of a momentary high pressure condition in the forward end of cylinder 234. This pressure is transmitted through line 230 which is blocked by valve V26. Fluid is therefore forced from regulating valve 216,

' installed in line 238, through line 218 and check valve 288 into line 226. When the pressure in cylinder 234 drops to a value equal to that maintained in line 226, check valve 288 closes and the momentum of carriage I38 has been controlled. The stopping of carriage I54 is similarly cushioned by allowing the high pressure to be dissipated from regulating valve 282, installed in line 242, through line 284 and check valve 286 into line 236.

The opening of contacts CBB opens the circuit LICSB-C I 8IBRI 8L2. de-energizing relay RI 8 and opening the two sets of contacts associated therewith. However, the relay RIO is energized again and its contacts closed by the 1 closing of contacts CBC which close a circuit L I LS4AC2 IB-'C8EC9CR I Il- L2. Opening of contacts C9B also opens the circuit LIC9BC22B--R22-L2 but relay R22 remains energized by the circuit through LILS4A The closing of limit switch contacts LSSA closes a circuit LI LS8B LS I 0 LSSA SW3A RI IL2, energizing relay RI I, closing contacts CI IA and CI IB and opening contacts CI IC and CI ID. The opening of contacts CI I C and CI ID has no effect on the cycle at this time. The closing of contacts CIIB closes a circuit LI- LS8B-LS I 8-CI I BSW3A-RI IL2 to provide a holding circuit for relay RI I. Closing of contacts CI IA closes a circuit LICI IA-S2IB-L2 to energize the solenoid 821B.

The closing of limit switch contacts LSI4A closes a circuit LILSI3B-LSIILSI4A SW4A-R23-L2, energizing relay R23, closing contacts C23A and 023B and opening contacts C230 and 023D. The opening of contacts 023C and C2 3D has no efiect on the cycle at this time. The closing of contacts C23B closes a circuit LILSI 3BLS I IC23BSW4A-R2 3L2 to 11 provide a holding circuit for relay R23. Closing of contacts C23A closes a circuit LI-C23A S24B-L2 to energize the solenoid S24B.

The energization of solenoid S21B reverses the position of the piston of valve V21 to permit hydraulic fluid to pass from supply line I80 through valve V21 and line 288 to the upper end or leadscrew nut operating cylinder 228 thus forcing leadscrew nut 229 to engage the leadscrew 290. Fluid is expelled from the lower end of cylinder 228 through line 226 and valve V21 into exhaust line 284. The energization of solenoid S24B reverses the position of the piston of valve V24 to permit hydraulic fluid to pass from supply line I82 through valve V24 and line 292 to the upper end of leadscrew nut operating cylinder 238 thus forcing leadscrew nut 240 to engage the leadscrew 284. Fluid is expelled from the lower end of cylinder 238 through line 238 and valve V24 into exhaust line 282. The engagement of both leadscrew nuts with their respective leadscrews causes tthe carriage I38 and I54 to advance at a rate proportional to the speed of rotation of the die heads which at this time will begin to cut threads of the desired characteristics on the opposite ends of difierent work pieces as explained above.

The movement of leadscrew nuts 229 and 240 actuates the limit switches LS1 and LSI2, opening contacts LS1A and LSI2A and closing LS1B and LSI2B. The opening of contacts LSlA and LSIZA has no immediate effect on the cycle. Closing of contacts 1513 and LSI2B closes a circuit LI-LS1B-LS I 2BC I 8D-RI 5L2 to energize relay RI5 and close its single set of contacts CISA. The closing of contacts CISA closes a circuit LICI5AS29A-L2, energizing solenoid S29A. The energization of solenoid S29A shifts the piston of valve V23 to permit fluid to pass from supply line 2 I2 through valve V29 and line 2I8 to the forward end of index operating cylinder II8 to force the withdrawal of the indexing member I20. Fluid is expelled from the rearward end of cylinder II8 through line 2I4 and valve V29 into exhaust line 254 while the indexing member I20 returns to its original position preparatory to reengaging the chain II8 for another forward indexing stroke.

At the beginning of its return stroke, the index mechanism actuates the limit switch LS4 to open its contacts LS4A and close contacts LS4B. Opening of contacts LS4A opens the circuit LILS4A-C21BC8E-C2 ICR22-L2, de-energizing relay R22 and opening its two sets of contacts. Opening of contacts LS4A also opens the circuit LILS4AC21BC8EC9C-RIO L2 to de-energize relay RIO and open its two sets of contacts. Opening of these four sets of contacts has no effect on the cycle at the present time.

At the end of its return stroke, the index mechanism actuates the limit switch LSI to open contacts LSIB and close contacts LSIA. The opening of contacts LSIB opens a circuit LI LSIBCI8C--RI8-L2 to de-energize relay RIG and open the four sets of contacts associated therewith. The opening of contacts CI8C, being in the last-named circuit, has no further effect on the cycle. The opening of contacts CI8A opens the circuit LICI8AS39L2 to de-energize solenoid $39. The opening of contacts CI8B opens the circuit LICI8B-S40L2 to de-energize solenoid S40. Therefore valve V39 is opened automatically to permit hydraulic fluid line 222 to valve 200. Valve V40 is also opened to permit fluid to pass from line I82 through valve V40 and line 224 to valve 202. Since the leadscrew nuts have been closed, there is no demand in the hydraulic system for a large volume of oil and the pressure in lines I80 and I82 rises. This pressure wave is transmitted from line I80 through valve V39 and line 222 to shift the piston of valve 200, shutting ofl the low pressure line 204 from pump I82. Both supply lines I10 and I80 are then supplied from the high pressure side of the pump, the sequence valve I18 permitting fluid to move from line I10 into line I80 to maintain the high pressure.

The high pressure wave on the right hand side of the system is transmitted from line I82 through valve V40 and line 224 to shift the piston of valve 202, shutting off the low-pressure line 208 from pump I88. Both supply lines I14 and I82 are then supplied from the high pressure side of the pump, the sequence valve I18 permitting fluid to move from line I14 into line I82 to maintain the high pressure. At this period in the cycle, the low pressure lines I88 and I12 from pumps I82 and I88 respectively are connected by valves 200 and 202 to exhaust lines 298 and 288.

Since check valves 2I8, 220, 212, and 214 prevent iuid from reaching lines 204 and 208, these lines are without pressure. The index mechanism is now retracted and fluid is contained in the system comprising cylinder I I8, lines 2l4 and 2I8, valve V28 and line 2I2 at zero pressure by means of the check valves 208 and 2 I0.

As carriage I38 advances, pressure is built up in the forward end of cylinder 234. The hydraulic system comprises means for regulating this pressure and using it as a cushioning means and for eliminating backlash between leadscrew and nut. This is done by setting the regulating valve 218 to a pressure against which the leadscrew can efliciently operate. When the pressure in line 230 exceeds this value, fluid escapes from valve 218 into line 218 and so through check valve 280 into line 228 which is now at zero pressure. The pressure in the forward end of cylinder 248 is similarly controlled by regulating valve 282.

Opening of contacts CI8D opens the circuit LI-LS1BLS I 2BC I 6D-RI 5L2 to de-energize relay RI5 and opening contacts CI5A. The opening of contacts CI5A opens the circuit LI CI5A-S29A-L2 to de-energize solenoid 829A. As the carriages move forward under the influence of their respective leadscrews, limit switches LS8 and LSI 4 are released, opening contacts LSQA and LSI4A and closing contacts LS9B and LSI4B. This opens the circuits LILS8B- LS I 0-LS9ASW3RI IL2 and LI-LS I 33 LSI I-LSI4A-SW4R23L2 but relays RH and R23 remain energized through their respective holding circuits described above.

When the carriages have carried their respective die heads forward far enough to have completed the threading operation, dogs 213 and 218 close limit switches LSI9 and LS20. Closing of limit switch LSI9 closes a circuit LI-LSI8- RI2-L2 to energize relay RI2 and close the five sets of contacts associated therewith. Closing of contacts CI2A closes a circuit LI-CI2AR,I8 L2 to energize relay RIB and close the four sets of contacts associated therewith. Closing of contacts CI8A closes a circuit LI-CI8A-S39-L2 to energize solenoid S39. Closing of contacts CI8B closes a circuit LICI6BS40-L2 to ento pass from line I80 through valve V38 and ergize solenoid S40. This energlzation of sole- 13 noids S39 and S40 restores the original condition in the hydraulic system preparatory to large volume demand on the system for the rapid withdrawal of the carriages from the work.

The closing of contacts CIGC has no immediate effect on the cycle. The closing of contacts 016D closes a circuit Ll-LSiB-LSi2B-Ci BDRI L2 energizing relay M5 and closing contacts Ci5A. Closing of contacts Cit/A. closes a circuit LiCi5AS29AL2 to energize solenoid SZSA. This does not alter the position of the valve V29 nor have any effect on the system.

The above described closing of contacts CIZB closes a circuit Ll- Ci2B--S3GB-L2 to energize solenoid 839B. Closing of contacts CI2C and CHE has no immediate effect on the cycle. Closing of contacts Ci2D closes a circuit Li-- LSiiBCl2DRl2-L2 to provide a holding circuit for relay RIZ. Closing of limit switch LSZii closes a circuit Ll--LS2@-R2 iL2, energizing relay R24 and closing the five sets of contacts associated therewith. Closing of contacts C24A closes a circuit LiC24ARit-L2 to provide a holding circuit for relay Rlii. Closing of contacts 02 3B closes a circuit Li-C24B-S3IB--L2 to energize solenoid SeiB.

Energization of solenoid S303 shifts the piston of valve V38 to permit hydraulic fluid to pass from supply line I89 through valve V39 and line 252 into the rearward end of the die head operating cylinder 25% and thus cause the chasers of die head I42 to be withdrawn radially from the thread cut so that the die head his be withdrawn axially to clear the work. Fluid is expelled from the forward end of cylinder 250 through line 248 and valve V to the exhaust line 254.

Energization of solenoid S3IB shifts the piston of valve V3! to permit hydraulic fluid to pass from supply line i 32 through valve Vill and line 269 into the rearward end of the right hand die head operating cylinder 2% and thus cause the chasers of die head it to be withdrawn radially from the thread cut so that the die head I may be withdrawn axially to clear the work, Fluid is expelled from the forward end of cylinder 253 through line 2% and valve V3] to the exhaust line 262.

Closing of contacts (324C and 025E has no immediate efiect on the cycle. Closing of contacts 026D closes a circuit Ll--I .Si3l3C2 iD R24 L2. The above described opening of both die heads causes the opening of limit switches LSlii and LSii. Gpening of switch LSlil opens the circuits L|-LSiiBLS i ilLS9A-SW3-Ri l L2 and LI-LSBB-LS I i-Ci ll3-SW3-RI i-- L2 which tie-energizes relay R1 1. The opening of switch LS5! opens the circuits LlL-S|3B LSIi -LSiiA-SW4R23 LS2 and LI LSI3B-LS1i-C23BSWt-R23L2 which deenergizes relay R215. The de-energization of relay R! 1 opens contacts Cl IA and Cl B and closes contacts Ci iC and Cl if). The opening of con tacts Ci i3 and C! K) has no immediate effect on the cycle. The opening of contacts C'i IA opens the circuit Li-CliA--S2TBL2 to de-energize solenoid SZlB. The closing of contacts CHD closes a circuit LlCliDCi2E-S2iA-L2 to energize solenoid 821A.

The de-energization of relay R23 opens the contacts 023A and C2313 and closes contacts C23C and C231). The opening or" contacts 023B has no immediate effect on the cycle. The opening of contacts C23A opens the circuit LiC23A S24B-L2 to de-energize solenoid $243. The

closing of contacts C23C closes a circuit LI C23C-Cl ICCIBCRI$L2, providing a holding circuit for relay RIG. The closing of contacts C23D closes a circuitLi-C23DC24E- S24A-L2 to energize solenoid 824A.

Energization of solenoid 521A by the de-energization of RH shifts the piston of valve V2! to permit fluid to pass from supply line I through valve V2! and line 226 into the lower end of cylinder 228 to force the piston thereof upwardly and thus disengage leadscrew not 229 from leadscrew 290. Fluid is expelled from the upper end of cylinder 228 through line 288 and valve V21 into exhaust line 254. Energization of solenoid S24A shifts the piston of valve V24 to permit fluid to pass from supply line I82 through valve V24 and line 236 into the lower end of cylinder 238 to force the piston thereof up wardly and thus disengage leadscrew nut 246 from leadscrew 294. Fluid is expelled from the upper end of cylinder 238 through line 292and valve V24 into exhaust line 262. With the leadscrew nuts disengaged, both carriages are brought to a full stop.

The opening of the leadscrew nuts actuates limit switches LS1 and LSI2, opening contacts LSIB and LSIZB and closing contacts LS'IA and LSIZA. The opening of contacts LS'I'B and LSIZB opens the circuit LlLS'lB-LSI2B Cl6DRI5--L2, de-energizing relay R15 and opening contacts CI5A. Opening of contacts C|5A opens the circuit Ll--Cl5A-S29AL2 to ole-energize solenoid 52 9A which has no immediate effect. The closing of contacts LS'IA closes a circuit Ll-LS8BLS1ACI2C -RI3-L2, energizing relay R13, opening contacts CI3B and CI3C and closing contacts CI3A and CiBD.

The opening of contacts C has no immediate effect. The opening of contacts CI3B opens the circuit LI--PBl8-PBl1C25BC|3B- C8CR8L2, de-energizing relay R8 and opening contacts CBA, 08B, CBC, and 08E and closing contacts C8D. The operation of the latter three sets of contacts have no immediate effect. The opening of contacts C8A opens a circuit Ll-Cl9A--C8A-S28AL2 to de-energize solenoid S2 8A. The opening of contacts 083 opens a circuit LlC'l8AC8B-S25AL2 to de-energize solenoid 525A. The closing of contacts 013D closes a circuit LiCl3D-Rl'i--L2, energizing relay RH and closing the two sets of contacts thereof. The closing of contacts CiiA closes a holding circuit for the relay, namely L|-CITARIIL2 while the closing of con tacts CIIB has no immediate effect. The closing of contacts CISA closes a circuit LICI3AS2EBL2 to energize solenoid $253. The closing of limit switch contacts LS! 2A closes a circuit Ll-LSI3B--LSl2A--4C2 iC-R2:i-L2, energizing relay R2 5, opening contacts C251? and 025C and closing contacts 025A and 02513. The operation of contacts C253 and C250 has no immediate effect while the closing of contacts C25D closes a circuit Ll-C2 5DR l 'i--L2 to provide a third circuit for the energization of relay RH. The closing of contacts 025A closes a circuit Li-C25AS23BL2 to energize solenoid 623B.

Energization of solenoid S263 shifts the piston of valve V26 to allow hydraulic fluid to flow from line I80 through valve V26 and line 230 into the forward end of cylinder 234 to start the left, hand carriage I38 moving rearwardly. Energization of solenoid 823B shifts the piston of valve V23 to allow fluid to flow from line I82 through valve V23 and line 242 into the iorward end of cylinder 246 to start the right hand carriage I54 moving rearwardly. Fluid is expelled from the rearward ends of cylinders 234 and 246 through lines 232 and 244 respectively and valves V25 and V23 into exhaust lines 254 and 262.

As carriages I38 and I54 start to move rearwardly, dogs 213 and 215 release limit switches LSIS and 1.520 and allow them to open. This opens the circuits LI-LSI9-RI2L2 and LI- LS2Il--R24-L2 with no immediate effect. Carriages I38 and I54 continue rearwardly until they reach their rearmost or loading position. Here, the limit switches LS8 and LSI3 are again actuated to open contacts 138B and LSI3B and close contacts LS8A and LSI3A. Opening of contacts LSBB opens the circuit LILS8B-CI2D-RI2- L2 to ole-energize relay RI 2 and open the five sets of contacts associated therewith. The opening of contacts CI2A opens the circuit LICI2A- RI6L2. Opening of contacts CI2B opens the circuit LI-CI2B-S30BL2 to tie-energize solenoid S3013. The opening of contacts CIZC' opens the circuit LI-LS8BLS1ACI 2C--R I 3-L2 de-energizing relay RI3, opening contacts CI3A and CI3D and closing contacts CI3B and CI3C. The closing of contacts CI3B and CI3C has no immediate effect. The opening of contacts CI3D opens the circuit LI-CI3DRII-L2. The opening of contacts CI3A opens the circuit LI CI3A-S26B-L2 to de-energize solenoid 526B. The opening of contacts CI2D has no immediate effect. The opening of contacts CI2E opens the circuit LICIIDCI2E-S2'IA-L2 to de-energize solenoid S21A.

Opening of contacts LSI3B opens the circuit LI-LSI3B-C24DR24L2, de-energizing relay R24 and opening the five sets of contacts associated therewith. The opening of contacts 024A opens a circuit LI-C24ARI6-L2. The opening of contacts 024B opens a circuit LI- C24B-S3IBL2 to de-energize solenoid S3IB. The opening of contacts C240 opens a circuit L I -LS I 3BLS I 2A-C24C-R2 -L2, de-energizing relay R25, opening contacts 025A and C25D and closing contacts C25B and C2 5C. The opening of contacts 025A opens a, circuit LI- C25A-S23BL2 to de-energize solenoid 523B. Closure of contacts C258 and C250 has no immediate effect. Opening of contacts C25D opens the circuit L-I-C25DRI'I-L2. The opening of contacts C24D has no immediate effect. The opening of contacts (324E opens the circuit LI- C23DC24E--S24A-L2 to de-energize solenoid S24A.

Of the solenoids thus tie-energized by the return of carriages I38 and I54 to loading position, only $2813 and 823B affect the cycle immediately. The de-energization of solenoid 826B permits the piston of valve V26 to occupy a neutral position and close all ports of the valve. Fluid is therefore trapped in cylinder 234 and lines 230 and 232 and carriage I38 stops. The momentum of carriage I38 causes a momentary increase in pressure in the rear end of cylinder 234 which is dissipated through line 232 and regulating valve 304 into exhaust line 254, thus providing a cushion to absorb the shock of the abrupt stopping of the carriage. In a similar manner, de-energization of solenoid S2313, permits the piston of valve V23 to occupy a neutral position, closing all ports to the valve and stopping carriage I54. The momentum of carriage I54 is cushioned against the fluid trapped in the rear end of cylinder 245 and the rise in pressure is dissipated through line 244 and regulating valve 306 into exhaust line 262.

lhe closing of limit switch contacts LSBA and LSI3A also closes a circuit LI-LSI3A-L38A C I 1BC8DC I 3CC2 5CRI 4-L2 to energize relay RI4 and close the two sets of contacts associated therewith. The closing of contacts CI4A closes a circuit LICI4AS28B-L2, energizing solenoid $288. The closing of contacts CI4B closes a circuit LI-CI4BS25BL2, energizing solenoid 825B. Energization of solenoid 828B shifts the piston of valve V28 to allow fluid to pass from line ITS through valve V223 and line IE8 to the upper end of cylinder I82 whereby rack I96 is forced downwardly and the grips of the left hand threading unit are opened to release the finished work. Energizaticn of solenoid 825B shifts the piston of valve V25 to allow fluid to pass from line I74 through valve V25 and line I90 to the upper end of cylinder I94 whereby rack I98 is forced downwardly and the grips of the right hand threading unit are opened. Fluid is expelled from the lower ends of cylinders I92 and I94 through lines 254 and 2&6 respectively and through valves V28 and V25 into exhaust line 254.

The opening of the grips on both threading units actuates the limit switches LS5 and LS6 to open contacts LSEA and LSGA and close contacts LSSB and LSGB. Limit switches LS2 and LS3 are also closed by this action and the closing of these last two serve the same purpose as pressing the cycle start button did at the beginning of the operation, that of energizing relay R6 which now occurs through the circuit LILSIA-I.S2- LS3C'iA-R6-L2. The system proceeds from this point, as described above, to perform another automatic cycle of operation.

To operate chucks independently To operate either chuck independently of the remainder of the machine, in order to test the gripping pressure, for example, or for any other reason, it is necessary to set switch SWI (Fig. 2C) on contact 13. This closes a circuit LI-SW2A- SWIBRI8--L2 to energize relay RIB, open contacts CISA and close contacts CIEB. Since the contacts CIBA are in the circuit of solenoid 525A, the opening of said contacts prevents the energization of said solenoid and therefore prevents the closing of the chuck I5-3 on the right hand threading unit I36. Button PBS is then pressed to close a circuit LISW2A--SWIB-PB6 C1CR2 I-L2, energizing relay R21, closing contacts 021A and opening contacts 021B. The closing of contacts (321A closes a circuit LI- SW2A-SWIBPB6CIC-C2IA R8 L2 to energize relay R8. Opening of contacts 0213 has no effect.

The energization of relay RS closes contacts C8A, (3813, C and CHE and opens contacts C8D. Closing of contacts C8A closes a circuit LI Cl9A-C8AS28AL2 to energize solenoid 828A which causes the closing of the chuck I46 of the left hand threading unit in the same manner as described above. The closing of contact C80 closes a circuit LIPBI8PBI1-C25BCI3B- C8CR8-L2, for holding relay R8 energized after pressure on push button PBS is released. The remaining contacts of relay R8 have no effect. To open the chuck I4 B, push button switch PBII lS pressed to open the circuit LI-PBI8 PBI'I- C25B-CI3BC8C-R8L2. Thus relay R3 is de-energized, contacts C8A, CIlB, C80 and CBE are opened and contacts SBD are closed. The opening of contacts CBA opens the circuit LI-- 17 CI9AC8A-S28AL2 to de-energize solenoid 828A. The opening of contacts 083, C80 and C8E has no eifect. The closing of contacts C8D closes a circuit LI--SW2A--SWIB-PBI'I C8DCI3C-C25C-Ri-.---L2, energizing relay RI4 and closing Chili. and CMB. Closing of contacts Cl lA closes a circuit LiCMAS2BBL2, energizing solenoid S288 and thereby causing the opening of the grips in the manner described above in the description of the complete cycle.

The right hand chuck I58 may be operated separately in exactly the same manner as above but by using SW2 instead of SWI, RI9 for RIB, solenoid 828A for SZBA, push button PB! for PBS, PBI'I for PBI8 PBIB for PBI'I, solenoids 825A and 253 for SZBA and 8283, etc.

Separate carriage operation The circuit provides for the separate operation of either carriage I38 or !54. Such operation is useful in setting up the machine for a particular size of work piece and especially for locating the dogs on the carriage so that the proper length of thread is generated. To initiate the movement of carriage I38, for example, it is necessary to open switch SWBA (Fig. 2A) and close SW3B (Fig. 2B). Push button switch PBB is then pressed to close a circuit LIClli!SW3B- PBB-RZil-LZ, energizing relay R213 and closing the four sets of contacts associated therewith. The closing of contacts C20A has no effect. The closing of contacts 029B closes a circuit LI- C23C-CI IC-C2ilBR.I5-L2, to energize relay RIG and close the four sets of contacts associated therewith. The closing of contacts 056A and CIGB closes respectively the circuits Ll- CI 6A-S39L2 and LI--CI6B-S4i!-L2 to energize solenoids S39 and $40 with the results already described in the operation of the entire machine.

The closing of contacts CIGC closes a circuit LI--C2L-CCIiC-CII3CRI%L2 to provide a holding circuit for relay RI= after button P338 is released. The closing of contacts CISD has no effect. The closing of contacts C2iiC closes a circuit LIC20C--LS8BC28A--RSL2, energiz ing relay RS. Closing of contacts 023!) closes a circuit LI-C2fiD-S3flA-L2 to energize solenoid 835A, which results in the closing to threading position of the die head I42 as described above. The energization of relay R9 closes contacts CQA and 09B and opens contacts C90. The closing of contacts 09A closes a circuit LI- C9A-S25A-ll=2 to energize solenoid 828A which, as in the above description of the main cycle of operation, causes the left hand carriage I38 to begin advancing toward the end of the work. The closing of contacts C913 closes a circuit LI- C9BLS9BC2liA-R9L2 to provide a second circuit for the energization of relay R9. The opening of contacts CBC has on eliect.

The closing of die head M2 closes the limit switch LSIII. The start of the advance movement of carriage I38 releases limit switch LS8, opening contacts LS'dA and closing contacts L333. When the carriage lfis has arrived at the point at which it is desired to stop the forward movement of said carriage, button PBS is released, opening the circuit LClESWi- PB8--R2Ei-L2. This ole-energizes relay R2,!) and opens contacts CZ JA which, in turn, opens circuits LiC2IiCLSlBC2AR9L2 and. LI-C9BLSB-C2EIA-L2. Thus relay R9 is de-energized, opening contacts CQA which opens the circuit Li -C9AS2 5AL2 and de-energizes 18 solenoid 826A, which, as described above, stops the carriage I38.

To return the carriage to its original loading position, the procedure is simply reversed by pressing push button switch PR5. This closes a circuit LI-LS8B-LS1A-PB5-Ri3--L2 to energize relay RI3 and close contacts Cii A. Closin of contacts CI3A closes a circuit Li-CI3A- S26B-L2, energizing solenoid SZtB and thereby starting carriage I38 rearwardly. The carriage stops as before, when valve V25 is freed by the deenergization of solenoid $263 which, in this case, takes place when button PBS is released.

If the button PS8 for starting the forward movement of the carriage, is held a suflicient length of time, limit switch LS9 will be actuated to stop the carriage automatically at the start of thread position, as follows. The actuation of limit switch LS9 results in the opening of contacts LS9B and the closing of contacts LSQA. Opening of contacts LSSB opens circuit LI- C2UCLS9BC2i3AR9-L2 and LiC9B LS9BC2ilA--R9L2 thereby tie-energizing relay R9 with the same results as are obtained if button P138 is released as described above. This operation leaves the carriage in position either to start the threading operation and thus continue the cycle or to be returned to loading position as also explained above.

It was seen above that release of button PBi! results in the de-energization of relay R28 and the opening of contacts 028A. Contacts CZSB also open, opening the circuit LI-C23CCI IC- C29BR.iiiL2. Contacts 0230 open with no eiiect. Contacts CZOD open, opening the circuit LI-C2!lD-S30A-L2 and de-energizing solenoid S3iJ-A. The de-energization of relay R9 described above also opens contacts 093 with no effect and closes contacts CBC.

Now, to continue the operating cycle it is necessary to return switches SW3A and SW3-B to their original positions, that is, to close SWSA and open SW33. This closes a circuit L!I.'S?l3-LSIii- LS9A-SW3A-RIIL2, to energize relay RII, closing contacts CIIA and OMB and opening contacts Cl IC and CI ID. Opening of contacts CIID has no effect. Closing of contacts CIIA close-s a circuit Li-CI IAS2?BL2 to energize solenoid SUB which, as described above, causes the left hand leadscrew nut 229 to engage lead screw 290. Thus the carriage begins to advance under leadsorew feed and a thread is generated on the work piece if one is in place in the chuck I46.

The closing of contacts Cl IB closes a circuit L I --LS 8B-LSI BC i IB-SW3A-Ri I-L2 to provide a holding circuit for relay R! I. The opening of contacts CI IC opens the circuit LI C23CCI ICC I 6C'-RIEL2, de-energizing relay RI6 and opening the four sets of contacts associated therewith. The opening of contacts CIGC and CI 6D have no effect. The opening of contacts CISA and CiSB opens the circuits LI-- CI5A-S39L2 and LlCI6B-S i0L2 respectively and de-energizes the solenoids S39 and S46 with the same results as described in the automatic cycle description above.

The closure of the leadscrew nut actuates limit switch LS! to open contacts LS'IA and close contacts LS'iB. As the carriage I38 begins to move forward under leadscrew feed, limit switch LS9 is again released, opening contacts LSSA and closing contacts LSSB. The opening of contacts LSQA opens the circuit LI-LS8B- LS!B LS9A-SW3A-RI I-L2. When the carriage acumen 19 has advanced far enough to cut the desired length of thread, the dog .213 closeslimitswitch "ISIS. This closes a circuit LII;S'[9-'R:I2L2 to energize relay RI2 and closeithe five'sets or" contacts associated therewith.

The closing of contacts .CIZA 'closes the circuit LICI2ARI6LZ, energizing relay RIG and closing its four sets of contacts. .Theclosing of contacts CIBA and CIBB close the "circuits LI-CI6AS39- L2 and LI-CIBB-S40 L2 to energize solenoids'S39 and S40 to cause the hydraulic system to supply a large'volume of'fluid to "the various cylinders as already described. .The closing of contacts CIBC and CI6D has no .effect. The closing of contacts CIZB closes the circuit LI-C I 2B-S30B---L2 to energize solenoid S30Band cause the die head I42 to open. The closing ofcontactsCIZC has no :e'iTect. Theclosing of contacts CI2D 'c'loses'a holding'circuit LI- LS8B'CI2D--RI2L2. Closing of contacts CI2Ehasno effect.

The opening of die head I42 opens limit switch LSIU, thereby opening the circuit '-LI1TS3B- LS III-CI IBSW3ARI IL2 rode-"energize relay RI I, open contacts CI IA and'CI IBand close contacts CI IC and CI ID. The opening of contacts CI IA .opens the circuit LI--CI IA'S2lB- L2 and thereby de-energizes solenoid -'SZ'IB. The opening of contacts CIIB has no effect. The closing of CI IC closes-the holding circuit.LI C23CCI IC-CI6CRI6L2. The closing of contacts CI ID closes a circuit LI-CI ID-C I 2E S2'IA L2 to energize solenoid SZ'IA which, as already explained, results'in the disengagement .of lead nut 229 from lead screw 290.

The movement of lead'nut'fls actuateslimit switch LS1, opening contacts LSIB and closing 'LSIA. The opening of contacts LS'IB has.no effect. The closing of contactsLS'IA closes acircuit L IlLS8BLS'IA.C I 2C-+RI 3L2 to energize relay RI3, thereby to close contacts .CI3A and CI3D and open contacts CI3B-and1Cl3C. The closing .of contacts .CI3A closes .a circuit LICI3A SZ6B-L2 and energizes solenoid SZBB which causes the carriage'to begin its re- CH3. Closure of contacts .CI'IBhas no effect" but the closing of contacts CI'IA closes a circuit LI-CIIARI'I-L2 to provide a holding circuit for relay RI 1.

As carriage I38 begins its return'movement, .limitswitchLSIBis opened, opening the circuit 'LI-'Li-SI9RI2L2. When carriage 138 has withdrawn to .the loading position,"limit "switch LS8 is actuated, opening contacts LSBBand closing contacts LSIB'A. Thelopening of contacts 'LSB-B opens the circuit LILS8B'CI-2D'RI2-L2'to .de-energize relay BIZ and open .the five sets of contacts associated therewith. .The opening of contacts CIZA opens the circuit LI-CI2A- RIB-L2. The opening of contacts CI2B 'opens the circuit LI-CI2BS30B-L2 to de-energize solenoid S3013. The opening of contacts .CIZC and LSSB opens the circuit "LILS8BLS'IA- C I 2C-R.I 3L2 :de-energizingrelay RI 3 ,;opening contacts CI3A and C I3D and :closing CI3B and CISC. The opening of contacts CI3A opens "the circuit LI-CI3A--S26BL2 to de-energize solenoid S263 and therebystop the carriage,

The opening of contacts CI3D opens the circuit LICI3DRI1L2. The opening of contacts CIZE opens are circuit LICI IDCI2E be apparent'that the left hand threading "unit I34 has now completed a cycle and ha returned to its original "condition without, however, 'being able to'repeat the cycle. It will be evident to those-skilled in the art that a similar operation may be carried out with the right hand threading unt I36, starting with the push button switch PBIIJ.

It will also be apparent that either threading unit-can be operated automatically and continuously together with the index mechanism but without the other threading unit by closing switch SWI to position SWIB to energize'relay RIB if it is desired to operate'the left hand unit I34 or by-closing switch SW2 to position SWIB to energize relay RIB if it .is desired to operate the right hand threading unit.

.Thisinvention may be embodied in other specific forms without departing from the spirit -or essential characteristics thereof.

close said gripper; a tool holding carriage; secand motor means operable to move said carriage in opposite directions with respect'to said gripper; a secondsolenoid operable when energized to control said second motor means to move said carriage in one direction; a first electric circuit including a first normally open switch for energizing said first solenoid; means for closing said'first switch; a second electric circuit including a second normally open switch for energizing said second solenoid; a first normally deenergizedrelay, operable to open said second switch when deenergized and'to close it when energized;

a third circuit including a third switch operative to be closed by the closing of said gripper and to energize said first relay when closed; a fourth electric circuit including a second normally denergized relay and a fourth normally open switch adapted to be closed to energize said second relay by the movement of the carriage in said one direction; a fifth electric circuit including a fifth switch adapted 'to be closed by 'said second relay when energized and to be opened by said second relay when deenergized, said fifth circuit including a third solenoid operable when energized by the closing of said-fifth switch to control said second motor means to move said carriage in the opposite direction; said second motor being ineffective when said second and third solenoids are deenergized; a sixthelectrical circuit including a sixth normally open switch operable when closed to maintain said second relay energized during the movement of said carriage in the said opposite direction; means operable to keep said sixth switch closed until said carriage reaches the end of its stroke in said opposite direction, comprising a third normally deenergizedrelay operable toclose said sixth switch only when energized, and. a seventh circuitincluding said "third relay and a holding circuit operable to hold said third relay energized during the movement of said carriage in said opposite direction; and a switch in said holding circuit operable to open to deenergize said third relay when said carriage reaches the end of the movement in said opposite direction, whereby said third solenoid is deenergized and said second motor is rendered ineifective to continue the movement of said carriage in said opposite direction.

2. In the machine described in claim 1, an eighth circuit including a fourth solenoid operable when energized to control said first motor mean to open said gripper, said eighth circuit including a switch operable to be closed by said carriage when reaching the end of its movement in said opposite direction whereby said fourth solenoid is energized to open said gripper.

3. In a machine of the class described, a work gripper; a first solenoid operative when energized to close said gripper; a first electric circuit including said first solenoid and a normally open first switch for energizing said solenoid when closed; a second electric circuit including a first relay operative to close said first switch when energized and to open it when deenergized, and a second normally open switch operative when closed to energize said relay; a third electric circuit including said relay and a third normally open switch operative to be closed by said relayv when energized to close a circuit for holding said relay energized; a tool holding carriage operative to reciprocate in opposite directions with respect to said gripper; means operative to move said carriage in one direction and then retract it; means responsive to said carriage when reaching the end of its stroke in said one direction to deenergize said relay, thereby opening said first switch and deenergizing said first solenoid; a second solenoid operative to open said gripper when energized; a fourth circuit including said second solenoid and a normally open fourth switch operable when closed to energize said second solenoid; and a fifth circuit including a second relay operative when energized to close said fourth switch and a normally open fifth switch operable to be closed by said carriage in reaching the end of its return stroke, said fifth circuit also including a normally closed sixth switch, said first relay being operable when energized to open said sixth switch and to close it when deenergized, whereby said second solenoid is energized to open said gripper in response to said carriage reaching the end of its return stroke.

4. In a machine of the class described, a work gripper; a hydraulic motor operable to close or open said gripper; a first solenoid operable when energized to control said motor to close said gripper; a first electric circuit including said first solenoid and a first normally open switch operable when closed to energize said first solenoid; a second circuit including a first relay, a second normally closed switch, and a third normally open switch operable when closed to energize said first relay, said third switch being connected to said relay for movement therewith to close and hold said first relay and said first solenoid energized when said first switch is open; means to momentarily open said normally closed second switch to thereby deenergize said first relay and said first solenoid; a third electric circuit including a normally closed fourth switch and a second relay connected to be energized when said fourth switch is closed, said fourth switch being connected to said first relay for movement therewith to open said fourth switch when said first relay is energized and to close said fourth switch when said first relay is deenergized; and a fifth electric circuit including a second solenoid operable when energized to control said motor to open said gripper in response to the energization of said second relay, whereby the momentary opening of said normally closed second switch is effective to deenergize said first solenoid and energize said second solenoid to open said gripper.

5. In the machine described in claim 4; a second work gripper including a second hydraulic motor operable to open and close it, a second pair of solenoids operable to control said second hydraulic motor to open and close said second work gripper, electric circuits in parallel with the aforementioned circuits and connected to said second pair of solenoids to energize them separately and including a normally closed switch having means to open it momentarily to open said second work gripper; and selecting switches in the circuits which energize said solenoids, said selecting switches being shiftable to prevent the energization of the solenoids controlling said first mentioned or said second hydraulic motor, whereby either work gripper may be operated independently.

6. In a machine of the class described, a pair of spaced machining units each operable to ma-.

chine different portions of a work piece; an indexing mechanism operable to transfer a work piece from the first of said machining units to the second, said machining unit being operable to simultaneously machine different portions of different work pieces in sequence; motor means operative to move said indexing mechanism through an advance stroke to simultaneously remove Work pieces from said machining units while feeding new work pieces simultaneously to said machining units, said motor means also being operative to move said indexing mechanism through a return idle stroke; a first electric circuit including a first solenoid operable when r energized to control said motor means to move said indexing mechanism through said advance stroke, and a normally open first switch operable when closed to energize said first solenoid; a second electric circuit including a first relay operable when energized to close said first switch, and a normally open starting switch operable to energize said first relay when momentarily closed; a third electric circuit including a normally open second switch operable when closed to keep said first relay energized after said starting switch is released, and a third switch in said third circuit operable to be opened by said indexing mechanism at the end of its advance stroke to deenergize said first solenoid; and a forth electric circuit including a second solenoid operable when energized to control said motor means to return said indexing mechanism, said fourth circuit including a fourth switch operable when closed to control the energization of said second solenoid, said indexing mechanism being operative to close said fourth switch at the end of its advance stroke.

ROY I. EYLER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,210,531 Englbaugh et al. Aug. 6, 1940 2,405,141 I-Iibbard Aug. 6, 1946 

